Some users have reported that clips that were working normally suddenly appear with missing media (checkerboard), even if they can confirm with a external browser that the media files are still accessible, so it should not happen.
It has only been reported on complicated Timelines with hundreds of clips (or long enumerated sequences), . In these cases Mistika works well until a certain point, then the missing media warnings start appearing (chequerboard images). If the user restart Mistika the problem is gone for a while, but it can happen again at some point
This is normally caused by having a small limit for an operating system setting, which is the maximun number of opened files. Increasing this limit will fix the problem
Please note that this is not a Mistika setting but an operating system one. Each operating system requires a different procedure to increase this limit. (please Google it for more details).
Note: For the particular case of Mistika Ultima, installing Mistika 8.8.1 (or later) will increase this limit automatically, so it should not be a problem anymore. But in the case of Boutique (windows and macOS) this is an Operating System setting that depends on each particular configuration, if you experience random missing media problems then you will need to increase the file limits manually.